Check whether any TCP port is reachable on a remote host. Essential for debugging firewalls, services, and network access rules.
nettoolz — port
// ready — enter a target above and press run
// api access
Use this tool via API
Integrate Port Checker into your own scripts or dashboards using our free JSON API.
# Port Check via APIcurl"https://nettoolz.co.uk/api/?tool=port&host=example.com&port=443"
// faq
Frequently asked questions
What does 'filtered' mean?
A filtered port means our probe received no response — typically because a firewall is silently dropping packets. This is different from 'closed', where the host actively rejects the connection with a TCP RST.
Which common ports should I know?
Port 22 (SSH), 25/587 (SMTP), 80 (HTTP), 443 (HTTPS), 3306 (MySQL), 5432 (PostgreSQL), 6379 (Redis), 8080/8443 (alternative web). Checking these helps verify services are accessible.
Why can I connect locally but not remotely?
Your server's firewall (UFW, iptables, or a cloud security group) is likely blocking inbound connections on that port. Check your firewall rules and ensure the port is open for external traffic.